1. Field of the Invention
The present invention relates to a navigation apparatus and a navigation system for displaying a current position of a mobile vehicle.
2. Description of the Related Art
Nowadays, a navigation apparatus for mounting in a vehicle, referred to as in-vehicle navigation system hereinafter, is commercially available, which utilizes GPS (Global Positioning System) satellites or the like to calculate a current position of a vehicle and display a mark indicative of the current position superimposed on a displayed map. Furthermore, a study has been made on a type of in-vehicle navigation apparatus having a communication function which transmits a current position mutually with a plurality of vehicles so that the positions of other vehicles as well as the position of the vehicle itself can be displayed on the some screen.
However, with such an in-vehicle navigation apparatus a problem may be encountered that, as the number of vehicles increases, a larger number of position marks appear on the display screen to result in an disorderly display, and also the position of the vehicle would be known to unintended third parties.
The present invention has been made to solve the above problem, and an object of the present invention is to provide a mobile vehicle navigation apparatus and a navigation communication system which are capable of offering a clear display and preventing vehicle position information from draining out to third parties.
A mobile vehicle navigation apparatus according to the present invention displaying the position of a mobile vehicle on a display, comprises a receiver for receiving information transmitted from another mobile vehicle, indicative of the position of the other mobile vehicle, a setting unit for setting the other mobile vehicle in either a valid state or an invalid state, and a display unit for displaying the position of the other mobile vehicle received by the receiver on the display when the other mobile vehicle is set in the valid state.
Also, a navigation communication system according to the present invention is comprised of a mobile vehicle navigation apparatus equipped in each of a plurality of mobile vehicles for displaying the position of the mobile vehicle on a display, and a communication service center, wherein the mobile vehicle navigation apparatus equipped in one mobile vehicle comprises an own position detector for detecting its own position, and a transmitter for transmitting position information indicative of the own position to the communication service center to transmit the position information to a mobile vehicle navigation apparatus equipped in another mobile vehicle, the communication service center comprises a receiver for receiving the position information transmitted from the mobile vehicle navigation apparatus equipped in the one mobile vehicle, and a transmitter for transmitting the received position information to a mobile vehicle navigation apparatus equipped in another mobile vehicle, and the mobile vehicle navigation apparatus equipped in the other mobile vehicle comprises a receiver for receiving the position information transmitted from the communication service center, and a display unit for displaying the position of the mobile vehicle on a display based on the received position information, wherein the position of the one mobile vehicle is displayed on the display of the mobile vehicle navigation apparatus equipped in the other mobile vehicle.